This invention relates to a gas turbine engine mount system and is particularly applicable to the mounting system of the engine to aircraft.
Historically, and conventionally the engine is typically mounted to the airframe by including structural load carrying members in the nacelle, pod, or pylon and attaching the engine to the airframe at least at two different planes along the axis of the engine. In certain installations where swivel-trunnion joints are utilized the trunnions may be either attached to the nacelle or engine case and the complementing swivel may be attached to the engine case or nacelle respectively. This becomes a design trade-off to determine the distribution of local bending moments between the nacelle and the engine.
It is also conventional in installations that utilize three swivel trunnion joints in a single plane to have the joints formed in various combinations of fixed and sliding joints which is predicated on where and how the additional point of support is applied. As for example, U.S. Pat. No. 3,006,587 granted to L. F. Junelle et al on Oct. 31, 1961 discloses a three swivel-trunnion joint (fixed and sliding) mounted in proximity to the engine's center of gravity (C.G.) and includes at another plane, a linkage support arrangement spaced fore or aft of the plane of the three swivel-trunnion joint.
We have found that we can simplify the mounting system of the engine to the airframe by locating three joints in a single plane transverse to the engine axis, where all the joints are fixed, save for a small radial movement on each joint to account for thermal expansion, wherein all of the applied loads (thrust, vertical, side and torque) are resolved in a single plane. While the plane may be selected close to the C.G. of the engine, this invention particularly contemplates the cantilever support of the engine. Obviously, the location of the mount system must be limited by the engine construction inasmuch as it must be located in proximity to a location in the engine where there is adequate rigid stiffness, as where the main bearings may be supported.
Additionally, this invention has the advantage of obviating the ovalization problem associated with thrust loadings that is sometimes evident in a multiple plane mounting system. This is particularly applicable in relatively long engine duct installations as is shown in the preferred embodiment. Hence by virtue of the invention the thrust load is spread out and carried uniformly through the fan exit case and long duct to the concentrated load attachment points.